James Mason is having an holiday in an hotel in France just before the outset of WWII. When he goes to collect some developed photographs he has taken, he is detained by the police who accuse him of illegally photographing sites around Toulon that might be of interest to the enemies of the Republic. It's pretty clear that the investigating officer believes his claims of innocence, but he is still sent back to keep tabs on the other guests at the hotel or face prison, deportation and quite possibly the Gestapo. The hotel has no shortage of likely suspects - Lucie Mannheim, Raymond Lovell and Herbert Lom to name but three, and he must try to find the would-be traitor without getting trapped in the web of intrigue that is clearly being spun around him. Mason engages us well, as does Lom and Frederick Valk and it's a bit like a game of Cluedo - there are plenty of clues and potential perpetrators and in the main, the story sustains quite decent degree of suspense before the villain is exposed and we are, sadly, delivered of a pretty flat conclusion. Still worth watching, though.